Water-resistant explosive compositions



WATER-RESISTANT EXPLOSIVE coMrosrrioNs Mario Scalera, Somerville, andMax Bender, East ramswick, N. L, assignors to American CyanarnidCompany, 'New York, N. Y., a corporation of Maine No Drawing.Application February 2, 1955 Serial No. 485,816

1a Claims. (Cl. 52-7 This invention relates to explosive compositions,and more particularly to improved ammonium nitrate blasting compositionsresistant to the action of Water and moisture, which comprises ammoniumnitrate, a sensitizer, and solid fuels such as cellulosic or othercarbonaceous materials. 7

Among the various types of blasting explosive compositions in use todayare those comprising ammonium nitrate admixed in various proportionswith sodium nitrate, various combustibles and a liquid explosive such asnitroglycerine, drip oil (dinitro-tcluenes), and the like. For certainuses, these compositions containing ammo nium nitrate are preferredoverother blasting compositions. However, during storage and use, thesecompositions show certain disadvantages in that they deteriorate uponcontact with moisture and water. In the handling and use of thesecompositions, often necessarily under adverse conditions, it isdifficult to avoid contact with moisture or water. In contact withwater, these explosive materials often absorb sufiicient Water either toshow poor strength characteristics or to become progressively inert todetonation. This causes additional hazards and expense in blastingoperations and this disadvantage becomes especially serious when theblasting composition is used in the wet bore holes often encountered inactual field conditions.

In the past many attempts have been made to improve the water resistanceand overcome the disadvantages of ammonium nitrate containing explosivecompositions. Most simply, the cartridges generally used as containershave been dipped in a paraffin wax or the like to seal them againstwater and moisture, but this has been only partly successful. Attemptshave also been made to achieve water resistance by admixture of variouswaterrepellent materials with the composition or by coating theparticles with water-repellent substances or metallic soaps, resins andthe like, but these have likewise been only partly successful.Incorporation of materials which swell when in contact with water isalso a method used in these attempts. The increase in volume whichresults when such a material is in contact with water partly tends toseal up the crack or fissure through which the water has entered andprevents further entry of water. However, this, at best, affords atemporary seal against further deterioration by water, since thematerials used in the past formed temporary gels which dispersed onfurther contact with water, thereby losing all the protection sought.

We have now found that ammonium nitrate blasting compositions can bemade which show a surprisingly high degree of water resistance overgreatly increased periods of time. These compositions contain an organicmaterial which, in its polymerized form, upon contact with water,becomes a non-peptizable hydrophilic network resistant 2,826,485 1QPatented M 1958 to further action of water. These networks are formed bycross-linking linear polymeric chains. The linear chains are formed fromwater-soluble ethylenic unsatuated monomers and not more than 50% of awaterinsoluble ethylenic monomer, not less than 0.5 mol percent of themonomeric units of the copolymer chain being joined by cross-linkings.By the use of such non-peptizable, three-dimensional molecular networksin blasting compositions, we have achieved a great deal more life underextremely adverse conditions of exposure to water than has heretoforebeen possible. The property of being non-peptizable is the importantnecessary characteristic, for without this resistance to dispersion onexposure to much more water, the increased protection which is theessence of our invention will not be achieved. If peptization occurs, asin prior compositions, the initial protection is dispersed and theblasting composition rapidly deteriorates.

The high degree of water resistance is maintained even on prolongedperiods of contact with Water so that an extreme degree of permanence ofWater resistance is achieved. This high degree of permanence of waterresistance is a most surprising feature of this invention. We believethat the high degree of permanence is due to the three-dimensionial,non-peptizable hydrophilic network structure, but we do not wish to belimited to any theory thereon. Heretofore, water swelling agents,including various resins and gums, have given some degree of protection,but the protection is definitely limited since continued exposure towater results in'peptization and deterioration of the swelling agent.

The water-resistant ammonia dynamite compositions of our invention areproduced by admixing the hydrophilic network forming organic materialswith known ammonium nitrate blasting compositions. The known ammoniumnitrate blasting composi ions may be varied to achieve propertiesappropriate for the various uses for which they are intended aspracticed by those skilled in the art.

The water resistance of the blasting compositions of our invention isbelieved to be due to the swelling action which results when thematerial comes in contact with water. The exact structure of thewater-resistant nonpeptizable hydrophilic network is not known, but itis believed to result from the combined polymerization and cross-linkingeffect of the polymeric materials used, resulting'in a three-dimensionalnetwork. The fact that it is three-dimensional is important since it isbelieved that it is due to this fact that the gels formed with Water arenon-peptizable.

The three-dimensional network may be achieved in a number of ways:

(1) It is possible to use monomers which are incorporated into thedynamite formulation along with polymerizing or complexing agents. Theseform on contact with water the non-peptizable hydrophilic network in theform of a three-dimensional hydrophilic network.

(2) A linear polymer, retaining functional groups presumablyperiodically placed, may be used for incorporation into the dynamiteformulation, with or without a metal complexing agent. On contact withWater, the linear polymer is cross-linked either by the metal complexingagent or, in the other type, by reaction of functional groups with oneanother to form this three-dimensional hydrophilic network.

(3) A copolymer, cross-linked by any means, is dried f 2,825,485 p a andadded in powdered form to the dynamite formulation. On contact withwater, the hydrophilic network material then again takes up water andproduces the nonpeptizable seal.

(4) A monomer containing two or more ethylenic groups, together with amonomer containing only one ethylenic group, is incorporated togetherwith a polymerization catalyst into the dynamite formulation. In thepresence of Water, polymerization to the three-dimensional hydrophilicnetwork occurs. Polymerizing agents in the form of peroxy compounds andthe like are usually used.

(5) Any combination of the 1, 2, 3, and 4, categories above with ametallic complexing agent or a polymerizing agent may also be present toaccelerate the formation of the three-dimensional hydrophilic network.

Various types of polymer-forming materials may be used. The essentialelement in obtaining non-peptizable gel-forming polymers is that thepolymers must be based on a water-soluble monomer of the ethylenic type,that is, containing the group The monomers of this type include acrylicacid, methacrylic acid, crotonic acid, itaconic acid, citraconic acid,maleic acid, maleic anhydride, acrylamide, methylacrylamide,methylene-bis-acrylamide, and other N-substituted acrylamides' andsimilar compounds. In. this group, also, is the theoretical compoundvinyl alcohol (which is actually non-existent in the monomeric formsince it tautomerizes to acetaldehyde). Polyvinyl alcohols and theircopolymers are prepared from vinyl acetate and its copolymers bysaponification of the ester groups. However, such polyvinyl alcohols areequally usable in our invention and the theoretical tautomeric monomerof vinyl alcohol is considered to be included in our term water-solublemonomers.

The water-soluble monomers can be used alone as homopolymers or can becopolymerized with up to 50% of. relatively water-insoluble monomers.The limit of 50% is for the copolymers derived from water-solublemonomers having polar ionic groups such as the carboxylate group. Whenthe water-soluble monomer has a less polar group such as the carboxamidegroup as, for example, acrylamide, the maximum allowable water-insolublecomonomer is decreased to about 25%. By water-insoluble monomer, it isnot meant to imply that these show no water-solubility, although manyare insoluble. Rather, it is meant that these monomers have relativelylow solubility in water, as compared to the very soluble monomersincluded in the class of watersoluble monomers described above. As arule of thumb, a solubility of less than by weight should be regarded asinsoluble. The water-insoluble monomers which may be used include mostethylenic compounds such as ethylene, vinyl acetate, acrylate esters,methacrylate esters, acrylonitrile, styrene, and similar compounds.

The copolymer chains are cross-linked to form a threedimensional networkof molecularly-bound atoms. The cross-linking must link at least 0.5molpercent of the monomeric units of the polymer chains. Below thisfigure, the gels obtained will tend to peptize. Above 0.5 mol percentthe gel becomes non-peptizing in the presence of excess water. It isthus usable for the protection of blasting material against exposure towater. Maximum results are obtained when the cross-linking joins 5-12mol percent of the monomeric units. Too great an amount of cross-linkingmay reduce below desir-able limits the ability of the cross-linkedpolymers to swell in water. The exact maximum of desired crosslinkingdepends on the cross-linking tobe used since, with covalentcross-linking, a joining of 5 8% of the monomers is preferred, but whenthe cross-linking is ionic, good results are obtained when 10,l 2% isused.

The cross-linking can be either ionic or covalent. Ionic cross-linkingis achieved by causing the reaction of polyvalent cations withcarboxylate groups on the polymer chains. Such polyvalent metal cationsas aluminum, copper, chromium, iron, calcium, magnesium and the like, ororganic polyamines such as ethylenediamine, diethylenetriamine,triethylenetetramine and the like can be used. In either case thepolymer chains and a salt of the cation are usually mixed with theexplosive. Contract with water produces cross-linkage by the formationof salts of the polyvalent cation or polyamine and the carboxylategroups of the polymer chains. It is also possible to form such salts bydrying and then adding them to the blasting mixture. When water contactssuch a blasting mixture, the dry salt reswells at the point of contactand protects the rest of the mixture. ionic cross-linking is not limitedto polymer chains and carboxylate groups since polyvinyl alcohol andcopolymers of vinyl alcohol such as partly hydrolyzed polyvinyl acetateor hydrolyzed polyvinyl styrene coploymers can be used similarly. Inthis case the cross-linking is achieved by the use of boric acid.

Covalent cross-links may be prepared by forming derivatives of themonomer to give a bifunctional monomer. As examples of this type, onecan use N,N'-alkylenebisacrylamides such as methylenebisacrylamide,vinyl esters of dibasic acids such as divinyl succinate and the like.Covalent cross-linking can be formed also by using monomers substitutedby functional groups capable of reacting with other groups or withunlike groups to form other chains in situ. As examples of this type onecan mention N-methylol acrylamide. In the presence of an acid catalystthe methylol groups of this monomer inter-react with other such groupsor with amide groups to form crosslinkage between the acrylamide units.Another possibility is to form cross-links from polymer chains and othermolecular materials included in the mixture. An example of this would bethe reaction of polyketone or glyoxal with polyvinyl alcohol. Such acompound can be prepared in situ on contact with water or can bepreformed and dried for inclusion in the explosive composition.

Any of these cross-links can be used in an explosive composition inwhich the monomers to be copolymerized are included in the explosivetogether with a polymerization catalyst. They may also be used asuncross-linked polymers to be cross-linked in situ on exposure to wateror as completely formed, dried, three-dimensional networks which swellon contact with water. When polymerization is to take place oncontactwith water, a'per salt peroxide or similar compound mustbeincludedin the mixture to catalyze the polymerization. Usually, one

uses potassium persulfate or ammonium persulfate for this purpose, andvery often to achieve a fast polymerization a bisulfite or thiosulfateis also included. When the cross-linking is to occur in situ as, forexample in the presence of methylol groups, an acid catalyst, usually anorganic acid such as oxalic or benzoic, or a substance like diammoniumhydrogen phosphate, is included in the mixture.

While our invention can use many different kinds of polymers, asdescribed, the dynamite compositions containing acrylic polymers orpolymer-forming materials are the preferred embodiment of our invention.It is with polymers of this type that we have achieved the bestprotection of blasting compositions from water deterioration. By acrylicpolymers or polymer-forming materials we refer to polymers of theacrylic type made up of units which in their unpolymerized form areacrylic acid and its functional derivatives such as acrylamide,acrylonitrile, and the like, possibly combined with other derivativeslike methylene bisacrylamide, methylol acrylamide and the like. Thesematerials as polymer units may be used. as

such or may be used in a partially polymerized or crosslinked form asexplained above to achieve the hydrophilic network of our dynamitecomposition.

In the. practice. of our invention, the. hydrophilic net- The use of Iwork materials are added to the ordinary ammonia dynamite formulationsand the resulting mixtures are then handled and processed by theordinary methods in the art. Various concentrations of the hydrophilicnetwork materials may be used, from about 0.2% to 8%. However, we preferto use from about 1-4%. As such agents there may be used variouscombinations of monomeric units either in the form of monomerscontaining only one ethylenic group, or of these mixed with monomerscontaining more than one ethylenic linkage (i. e. cross-linked beforepolymerization), or as chains to be cross-linked in situ, or as alreadyformed cross-linked, three-dimensional polymers which have been dried.Examples of the preferred ethylenic polymeror polymer-forming materialswhich may be used are acrylic acid, acrylamide, methylolacrylamide,methylenebisacrylamide and the like as watersoluble monomers, the lattertwo being examples of monomers capable of organic cross-linking and theacrylic acid being an example of a monomer capable of ioniccrosslinking. Acrylonitrile, acrylate esters and the like are thepreferred examples of water-insoluble monomers. These are used in theproportions of monomers and crosslinking previously described.

More specifically, in achieving the hydrophilic network in thecomposition of our invention according to the five categories above,there may be described as examples, the following combinations of theacrylic products which, when present in the dynamite, form an increasedvolume non-peptizable hydrophilic network upon contact with water.

(1) A mixture of acrylamide and acrylic acid together with a metal salt,preferably those with polyvalent cations such as aluminum, chromium,copper, iron, calcium, magnesium, and the like is used together withpotassium persulfate and sodium thiosulfate to catalyze polymerization.Organic polyvalent cations may also be used such as those formed fromtriethylene tetramine, ethylene diamine, and similar polyamines. In thepresence of water this forms the non peptizable hydrophilic network; themetal here probably takes part in the structure as a complexing agent orchelating agent to form the cross-links.

(2) A polyacrylamide-polyacrylic acid (either a copolymer formed bypartial hydrolysis of polyacrylonitrile or a mixture of homopolymers)containing in part carboxyl groups and in part carboxamide groups isused together with a metal salt, such as aluminum sulfate, etc., in theblasting compositions. The metal ion, on contact with water, cross-linksthe polymer chains by salt formation and/ or chelation.

(3) Acrylamide and methylene-bis-acrylamide is copolymerized in aqueoussolution, for example, using sodium thiosulfate and potassium persulfateas the catalyst system. This forms the three-dimensional polymer whichis then dried and pulverized and used as such in the blastingcomposition, to reswell when contacted by water. The metallic ions herefunction as polymerization catalysts and do not function as complexingor chelating agents. N-methylol polyacrylamide is also an example ofpolymers in this category usable in our process, but with this theremust also be included an acid catalyst to effect cross-linking throughthe methylol groups when Water comes in contact with the polymer chainsor the cross-linking must have been previously achieved.

(4) A mixture of acrylamide and methylene-bisacrylamide, along withvarious proportions of such catalysts as sodium thiosulfate andpotassium persulfate, is used. This is incorporated into the dynamiteformulation and forms the three-dimensional polymer, in contact withwater, by polymerization in situ.

(5) Any combination of categories 1-4 may be used.

The compositions of our invention show greatly improved water-resistanceproperties which have a remarkable degree of permanence. available inthe art for measuring the water resistance of dynamite compositions, itis extremely diflicult to By the use of the methods obtain reproducibleresults. Moreover, the methods used afford at best a determinationmerely of whether or not the deterioration caused by water has reachedsuch a state as to result in the composition being completely or in partinert to detonation. By the means known in the art, it is difficult ifnot impossible to obtain quantitative measurements as to the degree ofwater deterioration resulting from contact with water with varyingamounts of time, as shown by loss of strength of the explosion. In orderto demonstrate this surprising degree of water resistance of ourdynamite compositions, We have devised a method by means of which we canrepro' ducibly determine the degree of deterioration, that is, therelative loss of strength of the explosion resulting from exposure towater with varying periods of time and the limit of water exposurebefore the composition becomes inert to detonation. Described mostsimply, We determine the relative strength of theexplosion on partiallydeteriorated samples of the composition by measuring the intensity ofthe noise of the explosion; we have found that this gives a measurementof the relative strength of the explosion which is dependent upon thedegree of deterioration by exposure to water. This is further explainedbelow.

Our invention is further illustrated in more detail by the followingexamples.

EXAMPLE 1 Water-resistant explosive compositions These are prepared byadding from 1 to 4 parts of the indicated acrylic type hydrophilicnetwork-forming materials to about 100 parts of various ammonium nitratedynamite compositions. Examples of such compositions are:

nitroglycerin drip oil nitro cotton NaNO 8.0% starch 1.0% of a mixtureof a copolymer of 10% acrylic acid and acrylamide with 20% of its weightA1 (S0 .7H O

C 9.5% nitroglycerin 71.5% NH NO 1.2% NaNO 4.0% of a mixture of a driedcopolymer of methylolacrylamide (10% acrylamide (75%), andmethylmethacrylate (15%) with oxalic acid (3% of the mixture) and theusual combustibles 10.0% nitroglycerin 20.4% coarse NH NO 0.4% NaNO 2.0%of mixture of a copolymer of 50% acrylic acid and 50% styrene with about15% of its weight of chromic chloride amide, 70% acrylamide, and 25%acrylonitrile and the usual combustibles like wood flour, corn starch,

etc.

EXAMPLE 2 An explosive composition is prepared by adding from 1 to 4parts of the hydrophilic network forming material to a dynamiteformulation in substitution of the parts of starch as indicated. 7 Atypical formula is as follows:

Parts Ammonium nitrate 37.0 Sodium nitr 36.7

Corn starch r 8,0 Granulated coal 2.3

Wood pulp--- 1.0 Ground chalk 1.0 Nitro cotton 0.1 Drip oil 1.5Nitroglycerin 12.4

Thus, if 4 parts of the hydrophilic network forming material are added,only 4 parts of starch are used. The usual means of mixing as employedin the art are used.

The composition is then machinepacked uniformly into 1%" x 8 dynamitecartridges and subjected to the following testing methods, the resultsof which are given in the table below.

The water resistance of these formulations is determined by thefollowing procedure: The cartridges are completely sealed with a waxcoating (microcrystalline wax is preferable). The whole cartridge isfirst dipped in the wax. Then each end is dipped again and finally waxis ladled into the depressions in the ends. 'Holes,

2 mm. in diameter, and 17.5 mm. deep, are then punched.

into the cartridge perpendicular to its longitudinal axis; 16 holes areplaced in the cartridge in four staggered longitudinal rows of fourpunch holes each, each row being at 90 of arc to the other, the distancebetween holes in any one row being 1%" and from a given end of thecartridge, the nearest holes for alternate rows being 1 and 1%",respectively. Y a

The punched cartridges are then placed in a water bath, 9 from thesurface and firmly supported at the ends and middle in a level andhorizontal position, being so placed that the holes point in verticaland horizontal directions in the tank. After being thus exposed to theaction of water for various periods of time, the cartridges are removedand then detonated with a standard No. 6 blasting cap. The intensity. ofthe sound from the explosion of the immersed cartridges is compared withthe intensity of the sound from a control non-immersed cartridge of thesame formulation. The ratio of the sound intensity from an immersedcartridge to the sound intensity'of a non-immersed control cartridge isdesignated the relative sound intensity, (RSDQ' The sound intensity ofeach explosion is determined in a shooting house, 75 feet uphill fromthe shooting pit, both shooting pit and shooting house being locatedoutdoors in a convenient place such as in a ravine. Practically anysound measuring device may be used. When the readings are in decibels,which are equal to ten times log of the sound intensity, they areconverted to soundintensity for calculation of the relative intensity.

Examples of suitable apparatus are the following.

(1) General Radio Sound Survey Meter, type 1555-A. Here the maximumneedle deflection is measured. 7 Readings are in decibels. r

(2) General Electric Sound Survey Meter, Catalog 498017 ,S=G1. Here,-also, the maximum needle deflection is measured. Readings are also indecibels.

(3) Brush Electronic equipment, pen-recording type of sound measuringapparatus using a microphone, Brush BA 106; amplifier, Brush BL 905;recorded through a Brush recording oscillograph, Brush BL 202. Here thedisplacement of the pen as shown on the tracing is proportional to thesound intensity.

The noise of the blasting cap can be ignored since this is negligiblecompared with the noise of the exploding dynamite composition.

The cartridges are immersed for different periods of time and are thendetonated. The relative sound intensities as defined above and asobtained by detonating one or more immersed cartridges and comparingwith one or more dry cartridges, are then plotted against time (therelative intensity for no immersion is l) to give a curve from which maybe read the degree of failure from immersion in water at any particulartime up to the time of being inert to detonation. An example of such acurve where six cartridges are immersed for periods of 3, 6, 9, 12, 16,and 22 days is shown in the following figure:

Relative Sound Intensity TimeinDay-s The extent of deterioration for anygiven time may be determined from the curve. Thus, for example, the timeof- /a deterioration '(on the basis of relative sound intensity equal to0 .66) is 12 days.

Any particular point may be designated as the failure point; as timeprogresses, even though an explosion takes place, the decreased relativesound intensity indicates loss of strength of the explosion.

Evidence of stub, i. e. incomplete detonation, is noted by observation;thus, even when only part of the charge detonates there maystill be ameasurable sound intensity. For convenience for comparison purposes, thetime when /a deterioration has; taken place, as determined from thecurve, is used as the basis of comparison. This is an extremely usefultest for showing the degree of permanence of water resistance which isachieved, itbeing possible to follow the actual rate'of deterioration.

The results ofthis'test showing the rate ofdeterioration cannot bedirectly compared with the results in previously published tests sincethe other tests as carried out simply indicate the point in hours afterexposure to water at which the cartridge fails to detonate completely. 7Also these cartridges have been completely waxed to hermetically sealthem except for punched openings, while cartridges in previous testshave not always beenso treated. There may. be-considerable deteriorationof thecomposition before detonation fails completely. As stated, theevidence. of stub has beenthe only endpoint designated in previoustests. In the new test described it is possible to follow the progressof deterioration with time of exposure to water.

In the following table are shown the results of tests on typicalcompositions.

10 10. The compositions according to claim 9 in which the dryhydrophilic molecular network is a polyvalent cation salt of polyacrylicacid.

Percent of Percent Time of $4 Hydrophlllc Cornstarch Deteriora-Hydrophillc Network Forming Network Used In tion (RSI Evidence MaterialUsed Forming Formnlaequal to of Stub Material tion 0.667)

Used I Polyacrylamlde-polyaerylle acid prepared by partial hydrolysis ofpolyacrylamide tsmgtxed lwith in rgatit} 80 D D par p0 ymer pa s o um amup; (A1:(SO4):.7H:0) 1 7 11. 5 26 Same as above- 2 6 6. 5 l5. 5 i as ifitii eawn'ii' '1' an 4 4 22 oyacrya e e yene Acrylamlde (5%) 2. 5 5. 57.0 17 Polyacrylamlde 7 ryl i 4 4 10.0 22 3 5 6. 5 16 0 8 1.8 7

We claim:

1. An explosive composition resistant to deterioration on contact withwater which comprises ammonium nitrate, a sensitizer, a solid fuel andat least 0.5% by weight of materials which, in their polymerized form,are a hydrophilic, non-peptizable, three-dimensional network ofmolecularly boundatoms, said network being composed of chains of alinear polymer of an unsaturated monomer of the ethylenic type, at least50% of said monomeric units having at least one substituent group chosenfrom the group consisting of carboxyl, carboxamide, N-methylolcarboxamide, N,N'-methylene bis-carboxamide, carboxylic anhydride, andlower alkyl chains having a carboxylic acid substituent, said polymerchains being crosslinked by short chemically bound atom chains, saidcrosslinkings joining a minimum of 0.5 mol percent of the monomericunits of said polymer.

2. Compositions according to claim 1 in which the materials which intheir polymerized form are a hydrophilic, three-dimensional networkcomprising 0.5-8% of the explosive composition.

3. Compositions according to claim 1 in which the materials which intheir polymerized form are a hydrophilic, three-dimensional networkcomprising 14% of the explosive composition.

4. The compositions according to claim 3 in which the monomers have beenpolymerized but have not been cross-linked.

5. The compositions according to claim 4 in which the polymer chaincontains carboxyl substituents and the cross-linking means is apolyvalent cation.

6. The compositions according to claim 5 in which the polymer chaincontains acrylic acid units and the polyvalent cation is aluminum.

7. The compositions according to claim 4 in which the polymeric chain isa poly-N-methylolacrylamide and an acid catalyst is included to efiectcross-linking.

8. The product according to claim 7 in which the methylolacrylamide iscopolymerized with acrylamide.

9. The compositions according to claim 3 in which the monomers have beenpolymerized and cross-linked and the resultant hydrophilic network hasbeen dried.

11. The compositions according to claim 10 in which the hydrophilicnetwork is an aluminum salt of a copolymer of acrylic acid andacrylamide.

12. The compositions according to claim 9 in which the hydrophilic,three-dimensional molecular network contains units of an N-N'-alkyleneacrylamide.

13. The compositions according to claim 12 in which the said network isa copolymer of acrylamide with methylene bis-acrylamide.

14. The compositions according to claim 9 in which the said network is achain cross-linked through N-methylolacrylamide units.

15. The compositions according to claim 14 in which the said network isa copolymer of acrylamide with methylolacrylamide.

16. An explosive composition resistant to deterioration on contact withwater which comprises ammonium nitrate, a sensitizer, a solid fuel andfrom 1-4% by weight of unsaturated ethylenic monomers, at least 50% ofsaid monomers having at least one substituent group chosen from thegroup consisting of carboxyl, carboxamide, N-methylol carboxamide,N,N'-methylene bis-carboxamide, carboxylic anhydride, and lower alkylchains having a carboxylic acid substituent, a polymerization catalystand a means for cross-linking the ultimate polymer, said cross-linkingto join a minimum of 0.5 mol percent of the monomeric units of saidpolymer.

17. The product according to claim 16 in which one of the monomers is analkylene bis-acrylamide.

18. The compositions according to claim 17 in which the alkylenebis-acrylamide is methylene bis-acrylamide.

19. The compositions according to claim 18 in which there is alsoincluded acrylamide.

References Cited in the file of this patent UNITED STATES PATENTS2,314,832 Kirst et a1 Mar. 23, 1943 FOREIGN PATENTS 154,807 AustraliaMay 1, 1952

1. AN EXPLOSIVE COMPOSITION RESISTANT TO DETERIORATION ON CONTACT WITHWATER WHICH COMPRISES AMMONIUM NITRATE, A SENSITIZER, A SOLID FUEL ANDAT LEAST 0.5% BY WEIGHT OF MATERIALS WHICH, IN THEIR POLYMERIZED FORM,ARE A HYDROPHILIC, NON-PEPTIZABLE, THREE-DIMENSIONAL NETWORK OFMOLECULARLY BOUND ATOMS, SAID NETWORK BEING COMPOSED OF CHAINS OF ALINEAR POLYMER OF AN UNSATURATED MONOMER OF THE ETHYLENIC TYPE, AT LEAST50% OF SAID MONOMERIC UNITS HAVING AT LEAST ONE SUBSTITUENT GROUP CHOSENFROM THE GROUP CONSISTING OF CARBOXYL, CARBOXAMIDE, N-METHYLOLCARBOXAMIDE, N,N''-METHYLENE BIS-CARBOXAMIDE, CARBOXYLIC ANHYDRIDE, ANDLOWER ALKYL CHAINS HAVING A CARBOXYLIC ACID SUBSTITUENT, SAID POLYMERCHAINS BEING CROSSLINKED BY SHORT CHEMICALLY BOUND ATOM CHAINS, SAIDCROSSLINKINGS JOINING A MINIMUM OF 0.5 MOL PERCENT OF THE MONOMERICUNITS OF SAID POLYMER.